Hydrodynamic coupling device

ABSTRACT

A hydrodynamic coupling device, in particular a torque converter or fluid clutch, comprises a housing assembly, a turbine wheel provided inside the housing assembly, and a torque converter lockup clutch assembly for establishing a torque transmission connection as desired between the turbine wheel and the housing assembly. The torque converter lockup clutch assembly comprises at least one essentially annular friction element, which is connected to the turbine wheel for mutually rotating about a rotational axis, and a pressing element which is connected to the housing assembly for mutually rotating about the rotational axis. The at least one friction element can be subjected to the action of the pressing element in order to establish the torque transmission connection between the turbine wheel and the housing assembly. The ratio of a flow outside diameter in the area of the turbine wheel to a friction outside diameter of the at least one friction element ranges from 1.30 to 1.80, preferably from 1.35 to 1.70, and/or the ratio of a friction outside diameter of the at least one friction element to a friction inside diameter of the at least one friction element ranges from 1.10 to 1.25, preferably from 1.15 to 1.20.

PRIORITY CLAIM

This is a U.S. national stage of application No. PCT/EP01/08777, filedon 28 July 2001. Priority is claimed on that application and on thefollowing application: Country: Germany, Application No.: 100 50 729.8,Filed: 13 Oct. 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to a hydrodynamic clutch device,particularly a torque converter or fluid clutch, comprising a housingarrangement, a turbine wheel provided in the housing arrangement, alockup clutch arrangement by means of which a torque transmissionconnection can be produced selectively between the turbine wheel and thehousing arrangement, the lockup clutch arrangement comprising at leastone substantially annular friction element which is connected to theturbine wheel for rotating jointly about an axis of rotation and apressing element which is connected to the housing arrangement forrotating jointly about the axis of rotation and by means of which the atleast one friction element can be acted upon to produce the torquetransmission connection between turbine wheel and housing arrangement.

2. Description of the Related Art

In hydrodynamic clutch devices of the type mentioned above, particularlyin a state in which at least some of the torque to be transmitted alongan output powertrain is conducted from the housing arrangement to theturbine wheel via the lockup clutch arrangement, torsional vibrationsoccurring in the drive system can be contained in that a certain slip ispermitted in the lockup clutch arrangement, so that torque peaks canlead to a relative rotation between the housing arrangement and theturbine wheel. This results in a comparatively large load on thestructural component parts or surface regions coming into frictionalcontact with one another in the area of the lockup clutch arrangement,since the power losses which occur at least with greater torquefluctuations and which are contained by the slip are converted intoheat.

In order to meet the demands of increasing possible power losses in thearea of the lockup clutch arrangement, systems are known like those, forexample, disclosed in WO 00/03158. In the hydrodynamic torque converterknown from this reference, the lockup clutch arrangement has twofriction elements coupled with the turbine wheel such that they rotatejointly, an intermediate friction element which is coupled with thehousing arrangement for joint rotation being positioned therebetween.The individual friction surface regions are made to interact with eachother by the clutch pistons acting as pressing element. By providing aplurality of radially offset friction surface pairs which can be made tointeract with one another, the entire available friction surface can beappreciably enlarged without a substantial space requirement with theresult that the power loss occurring in slip operation is alsodistributed over a larger surface and can accordingly be carried off inan improved, faster manner.

SUMMARY OF THE INVENTION

It is the object of the present invention to further develop ahydrodynamic clutch device of the type mentioned in the beginning insuch a way that it has improved performance with respect to the demandsarising during operation, particularly the demands occurring in slipoperation.

According to the invention, a ratio of a flow outer diameter in the areaof the turbine wheel to a friction outer diameter of the at least onefriction element ranges between 1.30 and 1.80, preferably between 1.35and 1.70, and/or a ratio of a friction outer diameter of the at leastone friction element to a friction inner diameter of the at least onefriction element ranges between 1.10 and 1.25, preferably between 1.15and 1.20.

By means of the first step according to the invention, namely, preparinga determined ratio between the flow outer diameter and the frictionouter diameter of the at least one friction element, an appreciably morefavorable distribution of mass is obtained, which results in a lowermass moment of inertia. The second step according to the invention leadsto a lockup clutch arrangement with larger friction surface regions, sothat the occurring power losses can be better absorbed and transmittedto surrounding components or component groups.

It is preferably provided in the hydrodynamic clutch device according tothe invention that, in an area radially outside of the lockup clutcharrangement, the housing arrangement has a shape that is adapted to theouter circumferential contour of the lockup clutch arrangement and tothe outer circumferential contour of the turbine wheel. As a result ofthis step, the housing arrangement has greater rigidity particularly inits area which is also provided for the lockup clutch arrangement andfor the action of the latter. This causes an appreciably smaller bulgingor inflation of the converter housing under the fluid pressureprevailing in the interior of the converter housing, so that evenrelatively wide friction surface regions—measured in radialdirection—can not lead to edge loading of friction linings or the likeinduced by bulging. For example, it can be provided for this purposethat the housing arrangement is constructed in a first housing portionso as to surround the lockup clutch arrangement substantiallycylindrically and has, in a second housing portion adjoining the firsthousing portion, a shape which is curved in direction of the axis ofrotation and extends along the outer circumferential area of the turbinewheel.

According to another advantageous aspect of the present invention, itcan be provided that the at least one friction element is connected tothe turbine wheel so as to be essentially rigid against rotation by adriving element. Therefore, it is no longer necessary to couple the atleast one friction element to the turbine wheel via a torsionalvibration damper or the like with the result that the installation spacecan be used more efficiently and, in particular, the shape of thehousing arrangement mentioned above can be provided in a simple manner.

The efficient use of construction space can be further assisted in thehydrodynamic clutch device according to the invention in that thepressing element is connected to the housing arrangement so as to rotatejointly by a driving arrangement which is arranged essentially in theaxial area between the pressing element and the turbine wheel.

As was already stated, it is advantageous for increasing the effectivefriction surface region when a plurality of friction elements areprovided, wherein an intermediate friction element connected to thehousing arrangement for joint rotation is arranged between two frictionelements in each instance.

In order to further optimize the mass moment of inertia existing in thehydrodynamic clutch device according to the invention, a substantiallyannular first coupling element can be provided which is connected in itsradial inner area to an outer side of the housing arrangement,preferably by laser welding, and is constructed in its radial outer areafor coupling with a second coupling element which is fixedly connectedor connectable to a drive shaft.

A construction of a hydrodynamic clutch device which is particularlysimple to realize and which operates on the principle of a dual-linesystem can be achieved in that an interior space of the housingarrangement is divided by a pressing element into a first space in whichthe turbine wheel is arranged and a second space, and in that work fluidcan be introduced into the first space and work fluid can be conductedout of the second space, or vice versa, for an exchange of work fluidthat is provided in the interior. In order to enable an exchange offluid in a system of the type mentioned above also during the locked upstate, it is proposed that at least one fluid through-opening isprovided in the pressing element to enable an exchange of fluid betweenthe first space and the second space. Further, to enable a fluid coolingin the slip state, it is further suggested that a flow channelarrangement which is preferably arc-shaped is provided in a frictionsurface region of the at least one friction element. This flow channelarrangement is then preferably open toward the two spaces, so that apassage of fluid through the flow channel arrangement will take placedue to the pressure difference between the two spaces which exists inany case in the locked up state, and the heat energy occurring in thisspatial region can be carried off.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a partial longitudinal section through a hydrodynamicclutch device according to the invention;

FIG. 2 shows a modified embodiment form of the hydrodynamic clutchdevice shown in FIG. 1.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The hydrodynamic torque converter 10 shown in FIG. 1 comprises a housingarrangement which is designated in general by 12. This housingarrangement 12 in turn substantially comprises a housing cover 14 whichis fixedly connected in its radial outer area, for example, by welding,to an impeller wheel shell 16. The impeller wheel shell 16 is fixedlyconnected on the radial inside to an impeller wheel hub 18. At its innerside facing the interior space 20, the impeller wheel shell 16 carries aplurality of impeller wheel blades 22 arranged successively incircumferential direction. Together with the impeller wheel hub 18 andthe impeller wheel blades 22, the impeller wheel shell 16 substantiallyforms an impeller wheel 24. In its radial inner area, the housing cover14 has a central opening 26 in which a housing hub 28 is inserted. Inits area located near the axis of rotation A, the housing hub 28 carriesa centering pin 30 which is inserted into a corresponding centeringrecess of a drive shaft, not shown, e.g., a crankshaft, for aligning theaxis of rotation A of the torque converter 10 with respect to the axisof rotation of the drive shaft. Further, a turbine wheel which isdesignated generally by 32 is arranged in the interior 20 of the torqueconverter 10. This turbine wheel 32 comprises, in the radial outer area,a turbine wheel shell 34 which carries a plurality of turbine wheelblades 36 at its side facing the impeller wheel 24. On the radialinside, the turbine wheel shell 34 is fixedly connected to a turbinewheel hub 38, for example, by welding. The turbine wheel hub 38 in turncan be connected to a driven shaft, for example, a transmission inputshaft, so as to be fixed with respect to rotation relative to it.

A stator wheel 40 is provided axially between the impeller wheel 24 andthe turbine wheel 32. The stator wheel 40 comprises a plurality ofstator wheel blades 44 on a stator wheel ring 42, these stator wheelblades 44 being positioned between the radial inner end regions of theimpeller wheel blades 22 and the turbine wheel blades 36. The statorwheel ring 42 is supported via a freewheel arrangement, designatedgenerally by 46, on a supporting element, for example, a supportinghollow shaft, not shown, so as to be rotatable in one direction aroundthe axis of rotation A and blocked against rotation in the otherdirection. In axial direction, the stator wheel 40 is supported axiallyby two bearing arrangements 50, 52 with respect to the impeller wheel 24on one side and with respect to the turbine wheel 32 on the other side.The turbine wheel 32 is supported in turn axially at the housing hub 28by a bearing 54.

A lockup clutch arrangement, designated generally by 56, is provided toproduce a direct mechanical torque transmission connection between theturbine wheel 32 and the housing arrangement 12. This lockup clutcharrangement 56 comprises a clutch piston 58 which is held so as to beaxially displaceable by a radial inner cylindrical portion on an outercircumferential surface of the housing hub 28 with the intermediary of asealing element 60. A ring-shaped or star-shaped driving element 62 isfastened, for example, by laser welding, to an end face of the housinghub 28 facing the turbine wheel 32. This driving element 62 has, in itsradial outer area, an elastic arrangement, for example, one or more leafspring elements 64 by which the piston 58 is held so as to be axiallymovable with respect to the driving element 62 but not rotatable incircumferential direction around the axis of rotation A.

The lockup clutch arrangement 56 further comprises two plate elements orfriction elements 66, 68 which carry friction linings 70, 72, 74, 76 attheir respective axial end faces. In their radial outer area, respectivecarrier elements 77, 78 of the friction elements 66, 68 have teeth indriving engagement with corresponding teeth of an annular drivingelement 80. This driving element 80 is fastened to a surface region ofthe turbine wheel shell 34 again by laser welding, for example.Accordingly, a connection which is rigid with respect to rotation isproduced between the friction elements 66, 68 and the turbine wheel 32.

Located axially between the two friction elements 66, 68 is anintermediate friction element 82 having teeth in its radial inner area,which teeth engage corresponding teeth of a driving element 84 fastenedto the housing cover 14.

In order to produce the locked up state, the fluid pressure in a space86 in the housing arrangement 12, in which space 86 the turbine wheel 32is also arranged, is increased with respect to the fluid pressureprevailing in a space 88. This space 88 lies essentially between thepiston 58 and the housing cover 14, i.e., the interior 20 of the housingarrangement 12 is essentially divided into these two spaces 86 and 88 bythe piston 58. In order to increase the fluid pressure in the space 86,fluid can be introduced via a through-opening arrangement 90 in the areaof the stator wheel 40 by the fluid pump, not shown, via an intermediatespace formed, for example, between the driven shaft, not shown, and thesupporting hollow shaft. When not in the locked up state, the fluid canenter the space 88 from space 86 by flowing around the friction elements66, 68 and can flow to a central through-opening in the driven shaft viathrough-openings 92 which are provided in the housing hub 28 and extendradially inward and then to a fluid reservoir. In order to make possiblean exchange of fluid also in the locked up state in which the clutchpiston 58 is pressed against the friction element 68 and, basically inthe radial outer area, the space 88 is sealed with respect to space 86so as to be tight against fluid by means of the surface regions infrictional contact with one another, at least one through-opening 94 isprovided in the clutch piston 58, which through-opening 94 is locatedradially inside of an annular surface region thereof which frictionallycooperates with the friction lining 76 of the friction element 68.Further, the friction linings 70, 72, 74, 76 have lining grooves, forexample, with a curved contour, which open toward the space 86 in theradial outer area and open toward space 88 in the radial inner area, sothat the occurring friction heat can be guided off also in the locked upstate, particularly in the slip state, by fluid flowing through in theregion of the friction linings 70, 72, 74, 76.

As was already stated, it is advantageous, for example, in order toachieve a torsional vibration damping, to operate the lockup clutcharrangement 56 in a slip state so that a relative rotation between thehousing arrangement 12 and the turbine wheel 32 is possible at leastwhen torque peaks occur. By providing a plurality of friction surfacepairs which engage with one another frictionally, the entire availablefriction surface is increased, with the result that the occurring loadis distributed over a larger surface region and, therefore, thedissipation of heat can also be improved. In order to optimize orminimize the total mass moment of inertia, the friction outer diameter bof the friction linings 70, 72, 74, 76 is kept comparatively small.Accordingly, a ratio of the fluid flow outer diameter a whichapproximately corresponds to the outer diameter of the turbine wheel 32with respect to the friction outer diameter b is preferably in the rangeof 1.35 to 1.70. This means that the flow outer diameter a isappreciably greater than the friction outer diameter b.

Further, the value of the ratio between the friction outer diameter band the friction inner diameter c of the friction linings 70, 72, 74, 76is advantageously in the range of 1.15 to 1.20. This results in acomparatively large radial extension of the annular friction linings.Further, in order for this to be realized without difficulty inoperation, the housing 12 of the hydrodynamic torque converter 10 isconstructed in such a way that directly adjoining the radial outer areaof the lockup clutch arrangement 56, i.e., the radial outer area of thefriction elements 66, 68, in a first housing portion 96, the housingcover 14 extends approximately cylindrically or axially and thereforeruns close to the outer circumferential contour of the lockup clutcharrangement 56, which means that a stiffening of the housing arrangement12 is provided directly adjoining the lockup clutch arrangement 56 inthe radial outer area by means of the bent contour of the housing cover14. In the area near the turbine wheel 32 and turbine wheel shell 34,the housing cover 14 is curved in an arc shape in axial direction in asecond housing portion 98 which adjoins the first housing portion 96 orpasses into the latter and its shape is therefore adapted to the outercontour of the turbine wheel 32. This leads to a further stiffening ofthe housing arrangement 12 with the result that a bulging or inflationof the housing 12 which leads to edge loading in the area of thefriction lining 70 in which the latter contacts a substantially radiallyextending portion 100 of the housing arrangement 12 can be prevented dueto the work fluid which is provided under pressure in the interior 20.

This structure of the torque converter 10 according to the invention ismade possible essentially in that the friction elements 66, 68 areconnected to the turbine wheel shell 34 without providing a torsionalvibration damper in its radial outer area.

Of course, more than two friction elements 66, 68, for example, threefriction elements, and, in this case, a correspondingly larger quantityof intermediate friction elements 82 can be used in the torque converter10 according to the invention. Also, the basic concept can be used withonly one friction element. By combining the total friction surface—whichis increased nevertheless—with a torque converter principle of thedual-line system in which the work fluid is introduced into the space 86and guided out again via the space 88, a very functional high-powerconverter is obtained in which torque fluctuations can be contained inparticular through the slip operation of the lockup clutch arrangement56.

Another advantage of the torque converter 10 according to the inventionconsists in the way that the torque converter 10 is connected to a driveshaft. FIG. 1 shows an annular coupling element 102 which is bent inaxial direction and formed of sheet metal, for example. In its radialinner area, this coupling element 102 is preferably arranged at thehousing cover 14 by laser welding. Laser welding is advantageous in thiscase because it is carried out in the area in which the housing cover 14provides a friction surface at its inner surface and therefore anydeformation would be disadvantageous when carrying out a weldingprocess. In its radial outer area, the coupling element has a pluralityof nut elements 104 or the like. Screw bolts, or the like, connectingthe coupling element 102 with a flexplate or the like can be screwedinto these nut elements 104. This flex plate can then be screwed to acrankshaft flange or the like by its radial inner area in a manner knownper se. This economizes on weight in the radial outer area of the torqueconverter 10 and accordingly further reduces the mass moment of inertia.

A construction such as that shown in FIG. 2 can contribute to a furtherreduction in the mass moment of inertia. In principle, this constructionessentially corresponds to the embodiment form according to FIG. 1.However, it will be seen that the radial extension of the housing hub 28is appreciably reduced. Since the housing hub 28 is constructed as asolid metal part, this represents a considerable saving of weight and acorresponding reduction in the mass moment of inertia. It will be seenin the embodiment form according to FIG. 1 that approximately half ofthe radial extension between the friction outer diameter and the axis ofrotation A is occupied by the housing hub 28, while in the embodimentform according to FIG. 2 this value is in the range of one third. Inother respects, the embodiment form according to FIG. 2 corresponds tothe preceding embodiment form described above with reference to FIG. 1,and reference is had to the preceding comments.

Of course, changes can be made in various areas of the torque converteraccording to the invention without diverging from the principles of thepresent invention. For example, the intermediate friction element orintermediate friction elements could also be coupled directly with thepiston 58 so as to be fixed with respect to rotation relative to it.Also, the carrier elements 77, 78 of the friction elements 66, 68 couldbe bent in their radial outer area toward the flywheel to enable areduction in the axial extension of the driving element 80 away from theturbine wheel 32. The two carrier elements 77, 78 could also be benttoward one another in their radial outer areas so that the toothingarrangement of the driving element 80 can be reduced with respect to itsaxial extension. If it is necessary to provide a torsional vibrationdamper for reasons pertaining to vibrations or operation in variousdrive systems, this could be provided in the area radially inside thelockup clutch arrangement essentially axially between the clutch piston58 and the turbine wheel shell 34, where there is sufficient spaceavailable.

What is claimed is:
 1. A hydrodynamic clutch device comprising: ahousing; a turbine wheel mounted for rotation about an axis of rotationin the housing, said turbine wheel having an outer diameter whichapproximately corresponds to a fluid flow outer diameter; a lock-upclutch for selectively producing a torque transmitting connectionbetween the turbine wheel and the housing, said lock-up clutchcomprising at least one substantially annular friction element having afriction outer diameter and a friction inner diameter; and a pressingelement which can act on said at least one friction element to producesaid torque transmitting connection between the turbine wheel and thehousing, said pressing element being connected to the housing for jointrotation about the axis of rotation, wherein the ratio of the flow outerdiameter to the friction outer diameter is between 1.30 and 1.80.
 2. Ahydrodynamic clutch device as in claim 1 wherein the ratio of the flowouter diameter to the friction outer diameter is between 1.35 and 1.70.3. A hydrodynamic clutch device as in claim 1 wherein the ratio of thefriction outer diameter to the friction inner diameter is between 1.10and 1.25.
 4. A hydrodynamic clutch device as in claim 3 wherein theratio of the friction outer diameter to the friction inner diameter isbetween 1.15 and 1.20.
 5. A hydrodynamic clutch device as in claim 1wherein said lock-up clutch and said turbine wheel each have an outercircumferential contour and the housing has a shape which conforms tothe outer circumferential contour of the lock-up clutch and to the outercircumferential contour of the turbine wheel.
 6. A hydrodynamic clutchdevice as in claim 5 wherein said housing comprises a first portionwhich is substantially cylindrical and surrounds the lock-up clutch, anda second portion which is curved and extends along the outercircumferential contour of the turbine wheel.
 7. A hydrodynamic clutchdevice as in claim 1 further comprising a driving element which connectssaid at least one friction element to said turbine wheel so as to beessentially fixed against rotation relative to said turbine wheel.
 8. Ahydrodynamic clutch device as in claim 1 further comprising a drivingarrangement which connects said driving element to said housing, saidpressing arrangement being arranged axially between said pressingelement and said turbine wheel.
 9. A hydrodynamic clutch device as inclaim 1 comprising a plurality of said friction elements, said devicefurther comprising an intermediate element arranged axially between eachtwo friction elements, said intermediate element being connected to saidhousing for joint rotation.
 10. A hydrodynamic clutch device as in claim1 further comprising a substantially annular first coupling elementhaving a radial inner area connected to said housing and a radial outerarea with means for connecting said coupling element to a drive shaft.11. A hydrodynamic clutch device as in claim 1 wherein said housingcomprises an interior space which is divided by said pressing elementinto a first space in which said turbine wheel is arranged and a secondspace, wherein working fluid can be exchanged between said first spaceand said second space.
 12. A hydrodynamic clutch device as in claim 11wherein said pressing element has a fluid through-opening for exchangeof working fluid between the first work space and the second work space.13. A hydrodynamic clutch device as in claim 11 wherein said frictionelement comprises a friction surface having an arcuate flow channel.